

A006758


Number of strictly 2dimensional onesided polyominoes with n cells.
(Formerly M4114)


4



0, 0, 0, 1, 6, 17, 59, 195, 703, 2499, 9188, 33895, 126758, 476269, 1802311, 6849776, 26152417, 100203193, 385221142, 1485200847, 5741256763, 22245940544, 86383382826, 336093325057, 1309998125639, 5114451441105, 19998172734785, 78306011677181, 307022182222505, 1205243866707467, 4736694001644861, 18635412907198669
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OFFSET

0,5


COMMENTS

A000988 is the main entry for this sequence.
This version counts only polyominoes that are strictly 2dimensional  it excludes those where all the squares are in a single line. Thus a(n) = A000988(n)  1.  John Mason, Feb 18 2021
The value of a(11) in Table 1 (p. 366) of Lunnon (1975) is incorrect, and was corrected here by N. J. A. Sloane in 2011.  Petros Hadjicostas, Jan 11 2019


REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

N. J. A. Sloane, Table of n, a(n) for n = 0..45 [a(0)=0 inserted by Georg Fischer, Jun 25 2020]
W. F. Lunnon, Counting multidimensional polyominoes, Computer Journal 18 (4) (1975) 366367.


CROSSREFS

A000988 (= a(n) + 1) is another version. A column of A195738.
Sequence in context: A109311 A151350 A195741 * A123189 A219847 A047156
Adjacent sequences: A006755 A006756 A006757 * A006759 A006760 A006761


KEYWORD

nonn


AUTHOR

N. J. A. Sloane


EXTENSIONS

Edited by N. J. A. Sloane, Sep 23 2011
a(0)=0 inserted by Sean A. Irvine, Jun 24 2020
Name clarified by John Mason, Feb 18 2021


STATUS

approved



